Flexible heaters bonded to substrate for higher power density

Paul Boughton
Durex Industries is now offering silicone rubber heaters with factory vulcanisation in addition to silicone rubber heaters. Silicone heaters, with a continuous operating temperature range from -51 to +220 degrees C, can be powered at voltages up to 600V. Using proprietary techniques, Durex Industries prepares the part for factory vulcanisation of the silicone rubber heater. Then, through a controlled process of heat and pressure, the silicone rubber heater is bonded to the customer's part. The silicone rubber fills the microstructure of the part to ensure efficient heat transfer. Even complex parts are candidates for factory vulcanisation of silicone rubber heaters because of Durex Industries' extensive in-house tooling capabilities.
According to the company, factory vulcanisation of silicone rubber heaters provides the best possible bond, being superior to pressure-sensitive adhesives or room-temperature vulcanising silicones. With no adhesive layer present, heat transfer rates are increased. The standard construction places only 0.38mm of silicone rubber between the internal element and the customer's part. This allows the silicone rubber heater to be designed at higher power densities and increases heater life. While standard power densities for silicone heaters are in the region of 0.78W/cm2, factory vulcanisation to aluminum can support power densities of 1.55-3.1W/cm2 if operating temperatures are controlled.
Factory vulcanisation can be accomplished with both silicone wire-wound heaters and silicone etched heaters. Standard resistance densities for both types of elements can range up to 15.5ohms/cm2. Silicone etched heaters can be factory vulcanised up to dimensions of 30 x 152cm. Silicone wire-wound heaters can be factory vulcanised to customers' parts with standard processes up to dimensions of 61cm x 91cm. For larger sizes consult Durex Industries' technical support engineers.
For more information, visit www.durexindustries.com

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